1. Field of the Invention
The present invention relates to continuous metal casting. In particular, it relates to the continuous casting of metal using a plurality of molds arranged vertically in a column, each mold separable into sections, such that the bottom mold is removed and placed on top of the column to form a continuous casting column.
2. Description of the Prior Art
Metal casting has been traditionally done using molds having individual and separated cavities for each part or item that is being molded. This molding procedure constitutes a "batch" type of process wherein the mold is reused. A batch process is inefficient in both the usage of labor and capital equipment since the mold is oftentimes being used to cool metal already solidified to a temperature in which it can be handled.
There have been several attempts in trying to develop continuous metal casting processes. The Waring U.S. Pat. No. 3,771,586 describes a continuous casting apparatus that includes a plurality of mold halves attached to two continuous vertical belts which bring the mold halves together to form a continuous casting column and which then separate the molds at a lower position, revealing the solidified metal. Although the Waring Patent describes a continuous caster, the continuous caster of the Waring Patent has half the molds not being used to cast metal at any one time. Since the molds are expensive, unnecessary capital is being used.
The Hallsworth U.S. Pat. No. 2,843,895 describes a wheel-type caster having individual molds disposed on the wheel and which are presented in a sequence to a pouring location, a molding box unloading station and a molding box loading station. Although the apparatus of the Hallsworth Patent may produce castings in a continuous manner, the molding process itself is still a batch process since each individual mold produces individual separate castings.
The Nakagawa U.S. Pat. No. 2,184,257 is similar in concept to the Hallsworth Patent in that it shows a centrifugal hollow ball casting machine in which individual molds are carried on an endless chain belt. The molds are charged with molten metal and rotated by an endless belt so that the molten metal inside the cavity is slung and distributed closely onto the cavity surfaces to form a hollow ball. However, each mold produces a distinct casting and in itself is a batch mold.
Further attempts in trying to develop a continuous casting process are described in the Green U.S. Pat. No. 1,863,371 and the Brinton U.S. Pat. No. 2,486,388. The Greene Patent shows a vertically disposed wheel having a plurality of molds disposed adjacently along the periphery of the wheel. Each of the molds is separated into two hinged halves. At a molten metal pouring position, the halves are brought together due to the rotation of the wheel and then opened when the metal has solidified dropping out the casting. The molten metal is continuously poured and the balls continuously drop out of molds that are being opened. However, such an arrangement is quite expensive since a large number of molds are needed and the wheel to rotate the molds must be structurally strong enough to handle the number of molds needed.
The Brinton Patent describes an apparatus that has a plurality of molds disposed on an inclined frame with two channels. The molds in the first channel proceed downwardly along an incline past a molten metal pouring station in which molten metal is poured along a slot in the mold and flows into the mold cavity. Each mold section defines a mold cavity with an adjacent mold section. When the metal has hardened at the bottom of the incline, the bottom-most mold section is broken away and pushed to a second channel on the incline, dropping the casting. The second channel on the incline includes a row of mold sections that are progressively pushed upwardly to resupply the first channel with usable molds. Again, this type of continuous metal casting process needs an excessive number of expensive molds.
In a plastic molding process, described in the Hegler et al U.S. Pat. No. 4,212,618, a plurality of molds are disposed in a horizontal row with the front end of the row being connected to an extruder from which molten plastic is supplied. A solidified plastic pipe exits the back end of the row. A plurality of rollers move the row of molds away from the extruder and a pair of arms grasp the mold halves at the end of the molding run and return the molds back toward the front end near the extruder. Although this is a continuous process, it is a plastic extrusion process unsuitable for processing of molten metal.